Linear mixed model better than repeated measures analysis

2019 ◽  
Vol 30 (6) ◽  
pp. NP1-NP2 ◽  
Author(s):  
Işıl Kutluturk Karagoz ◽  
Berhan Keskin ◽  
Flora Özkalaycı ◽  
Ali Karagöz
Keyword(s):  
Mixed Models ◽  
Repeated Measures ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Linear Time ◽  
Case Series ◽  
Model Fit ◽  
Repeated Measures Analysis ◽  
Technical Issues ◽  
Better Than

We have some criticism regarding some technical issues. Mixed models have begun to play a pivotal role in statistical analyses and offer many advantages over more conventional analyses regarding repeated variance analyses. First, they allow to avoid conducting multiple t-tests; second, they can accommodate for within-patient correlation; third, they allow to incorporate not only a random coefficient, but also a random slope, typically ‘linear’ time in longitudinal case series when there are enough data and patients’ trajectories vary a lot and improving model fit.

scholarly journals Infant and Toddler Consumption of a Lipid Nutrient Supplement After a 2-Week Home Repeated Exposure

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1017-1017
Author(s):  
Susan Johnson ◽  
Allison Shapiro ◽  
Kameron Moding ◽  
Kathryn Davis ◽  
Allyson Montalvo ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Repeated Exposure ◽  
Age Group ◽  
Global Alliance ◽  
Funding Sources ◽  
Nutrient Supplement ◽  
Alternate Version ◽  
Better Than

Abstract Objectives Repeated exposure (RE) paradigms produce improvements in food acceptance during infancy, however, less is known about RE effectiveness in toddlers. Here we examine the effects of RE on acceptance of sweetened and unsweetened versions of a lipid nutrient supplement (LNS). Methods Mothers and children (n = 56, 86% NonHispanic White), aged 7–11.30 mo (n = 12; infants) and 12–24 mo (n = 44; toddlers), participated in a randomized, 2-week home exposure study and 2 lab visits (Baseline [V1] & Post-exposure [V2]). Children were randomized to RE of 1) sweetened or 2) unsweetened versions of the LNS mixed into oatmeal. At V1, mothers offered version 1 of LNS (sweetened or unsweetened) until the child took 2 bites or refused 3 times. Then mothers fed the alternate version ([HE]; the LNS to which children were randomized for home exposure) until the child refused to eat more. Intake (g) of HE was measured. Mothers were given 10 servings of the HE version and told to offer their child the 10 servings over the following 2-week period. At V2, mothers again fed unlimited amounts of HE until the child refused to eat more and intake in grams was again measured. A linear mixed model for repeated measures tested change in intake of HE across V1 and V2 by age group (toddlers v. infants) and by LNS version (sweetened v. unsweetened). Significance of the statistical interaction (visit by age group and visit by version) was defined at P < 0.1. Results Fifty-five dyads (98%) completed V1 and V2. Caregivers offered their children, on average, 9 of 10 possible home exposure servings. Observed intake of the HE differed by age group (infants, V1 = 32.3 g ± 15.8, V2 = 28.8 ± 20.9 vs. toddlers, V1 = 15.5 g ± 16.3 V2 = 23.9 ± 19.5; P = .006). The linear mixed model confirmed (F = 3.41, P = .07) that intake of HE significantly increased from V1 to V2 in the toddler group, whereas intake in the infant group remained consistent between V1 and V2. The unsweetened version was preferentially consumed compared to the sweetened version (P = .07). Conclusions Children consumed the unsweetened version as well, if not better, than the sweetened version of the supplement. Over time, infants were consistent in their willingness to consume the supplement whereas toddlers showed an increase in intake, suggesting that toddlers may learn to eat the supplement through RE. Funding Sources Global Alliance for Improved Nutrition.

Long-term seizure outcomes after pediatric temporal lobectomy: does brain MRI lesion matter?

2019 ◽  
Vol 24 (2) ◽  
pp. 200-208
Author(s):  
Ravindra Arya ◽  
Francesco T. Mangano ◽  
Paul S. Horn ◽  
Sabrina K. Kaul ◽  
Serena K. Kaul ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Hippocampal Sclerosis ◽  
Brain Mri ◽  
Temporal Lobectomy ◽  
Seizure Freedom ◽  
Seizure Onset

OBJECTIVEThere is emerging data that adults with temporal lobe epilepsy (TLE) without a discrete lesion on brain MRI have surgical outcomes comparable to those with hippocampal sclerosis (HS). However, pediatric TLE is different from its adult counterpart. In this study, the authors investigated if the presence of a potentially epileptogenic lesion on presurgical brain MRI influences the long-term seizure outcomes after pediatric temporal lobectomy.METHODSChildren who underwent temporal lobectomy between 2007 and 2015 and had at least 1 year of seizure outcomes data were identified. These were classified into lesional and MRI-negative groups based on whether an epilepsy-protocol brain MRI showed a lesion sufficiently specific to guide surgical decisions. These patients were also categorized into pure TLE and temporal plus epilepsies based on the neurophysiological localization of the seizure-onset zone. Seizure outcomes at each follow-up visit were incorporated into a repeated-measures generalized linear mixed model (GLMM) with MRI status as a grouping variable. Clinical variables were incorporated into GLMM as covariates.RESULTSOne hundred nine patients (44 females) were included, aged 5 to 21 years, and were classified as lesional (73%), MRI negative (27%), pure TLE (56%), and temporal plus (44%). After a mean follow-up of 3.2 years (range 1.2–8.8 years), 66% of the patients were seizure free for ≥ 1 year at last follow-up. GLMM analysis revealed that lesional patients were more likely to be seizure free over the long term compared to MRI-negative patients for the overall cohort (OR 2.58, p < 0.0001) and for temporal plus epilepsies (OR 1.85, p = 0.0052). The effect of MRI lesion was not significant for pure TLE (OR 2.64, p = 0.0635). Concordance of ictal electroencephalography (OR 3.46, p < 0.0001), magnetoencephalography (OR 4.26, p < 0.0001), and later age of seizure onset (OR 1.05, p = 0.0091) were associated with a higher likelihood of seizure freedom. The most common histological findings included cortical dysplasia types 1B and 2A, HS (40% with dual pathology), and tuberous sclerosis.CONCLUSIONSA lesion on presurgical brain MRI is an important determinant of long-term seizure freedom after pediatric temporal lobectomy. Pediatric TLE is heterogeneous regarding etiologies and organization of seizure-onset zones with many patients qualifying for temporal plus nosology. The presence of an MRI lesion determined seizure outcomes in patients with temporal plus epilepsies. However, pure TLE had comparable surgical seizure outcomes for lesional and MRI-negative groups.

scholarly journals Mood and Global Symptom Changes among Psychotherapy Clients with Depressive Personality

2012 ◽  
Vol 2012 ◽  
pp. 1-12
Author(s):  
Rachel E. Maddux ◽  
Lars-Gunnar Lundh
Keyword(s):  
Repeated Measures ◽  
Mixed Model ◽  
Psychological Symptoms ◽  
Self Report ◽  
Treatment Results ◽  
Repeated Measures Analysis ◽  
Depressive Personality ◽  
Symptom Changes ◽  
Psychotherapy Clients ◽  
Over Time

The present study assessed the rate of depressive personality (DP), as measured by the self-report instrument depressive personality disorder inventory (DPDI), among 159 clients entering psychotherapy at an outpatient university clinic. The presenting clinical profile was evaluated for those with and without DP, including levels of depressed mood, other psychological symptoms, and global severity of psychopathology. Clients were followed naturalistically over the course of therapy, up to 40 weeks, and reassessed on these variables again after treatment. Results indicated that 44 percent of the sample qualified for DP prior to treatment, and these individuals had a comparatively more severe and complex presenting disposition than those without DP. Mixed-model repeated-measures analysis of variance was used to examine between-groups changes on mood and global severity over time, with those with DP demonstrating larger reductions on both outcome variables, although still showing more symptoms after treatment, than those without DP. Only eleven percent of the sample continued to endorse DP following treatment. These findings suggest that in routine clinical situations, psychotherapy may benefit individuals with DP.

scholarly journals Joint modeling of multiple repeated measures and survival data using multidimensional latent trait linear mixed model

2018 ◽  
Vol 28 (10-11) ◽  
pp. 3392-3403 ◽  
Author(s):  
Jue Wang ◽  
Sheng Luo
Keyword(s):  
Survival Data ◽  
Repeated Measures ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Proportional Hazards Model ◽  
Latent Trait ◽  
Joint Modeling ◽  
Fine Motor ◽  
Terminal Event ◽  
Longitudinal Outcomes

Impairment caused by Amyotrophic lateral sclerosis (ALS) is multidimensional (e.g. bulbar, fine motor, gross motor) and progressive. Its multidimensional nature precludes a single outcome to measure disease progression. Clinical trials of ALS use multiple longitudinal outcomes to assess the treatment effects on overall improvement. A terminal event such as death or dropout can stop the follow-up process. Moreover, the time to the terminal event may be dependent on the multivariate longitudinal measurements. In this article, we develop a joint model consisting of a multidimensional latent trait linear mixed model (MLTLMM) for the multiple longitudinal outcomes, and a proportional hazards model with piecewise constant baseline hazard for the event time data. Shared random effects are used to link together two models. The model inference is conducted using a Bayesian framework via Markov chain Monte Carlo simulation implemented in Stan language. Our proposed model is evaluated by simulation studies and is applied to the Ceftriaxone study, a motivating clinical trial assessing the effect of ceftriaxone on ALS patients.

Effects of a Combination of Stances and Points of Aim on Putting Accuracy

1988 ◽  
Vol 66 (1) ◽  
pp. 139-143 ◽  
Author(s):  
Erich Gott ◽  
Carl Mc Gown
Keyword(s):  
Analysis Of Variance ◽  
Repeated Measures ◽  
Traditional Method ◽  
Constant Error ◽  
Popular Opinion ◽  
Variable Error ◽  
Repeated Measures Analysis ◽  
Better Than

The purpose of this study was to determine the effects of two putting stances (conventional versus side-saddle) and two points of aim (ball versus hole) on putting accuracy. Subjects (12 men, 4 women) were taught to putt using four methods: (a) conventional stance, eyes on the ball; (b) conventional stance, eyes on the hole; (c) side-saddle stance, eyes on the ball; and (d) side-saddle stance, eyes on the hole. Each subject practiced each method for 2 wk., after which they were tested for purring accuracy by counting putts made, determining constant error, and by calculating variable error. Accuracy was assessed at 5 and 15 ft. A 2 by 2 repeated-measures analysis of variance showed that there was no single combination of stance and point of aim that was significantly better than another at either distance. This suggests that, contrary to popular opinion, the traditional method of putting is not the best method for putting; other methods are equally as good and could be used if individually desired.

Full Credibility with Generalized Linear and Mixed Models

2009 ◽  
Vol 39 (1) ◽  
pp. 61-80 ◽  
Author(s):  
José Garrido ◽  
Jun Zhou
Keyword(s):  
Mixed Models ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Linear Models ◽  
Link Function ◽  
Analysis Method ◽  
Risk Class ◽  
Statistical Analysis Method ◽  
Car Insurance ◽  
Insurance Data

AbstractGeneralized linear models (GLMs) are gaining popularity as a statistical analysis method for insurance data. For segmented portfolios, as in car insurance, the question of credibility arises naturally; how many observations are needed in a risk class before the GLM estimators can be considered credible? In this paper we study the limited fluctuations credibility of the GLM estimators as well as in the extended case of generalized linear mixed model (GLMMs). We show how credibility depends on the sample size, the distribution of covariates and the link function. This provides a mechanism to obtain confidence intervals for the GLM and GLMM estimators.

scholarly journals Which Test of Divergent Thinking Is Best?

2016 ◽  
Vol 3 (1) ◽  
pp. 4-18 ◽  
Author(s):  
Mark A. Runco ◽  
Ahmed M. Abdulla ◽  
Sue Hyeon Paek ◽  
Fatima A. Al-Jasim ◽  
Hanadi N. Alsuwaidi
Keyword(s):  
Divergent Thinking ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Mixed Model Analysis ◽  
Demographic Questionnaire ◽  
Problem Generation ◽  
Behavior Scale ◽  
Realistic Problem ◽  
Post Hoc ◽  
Better Than

AbstractDivergent thinking (DT) tests are probably the most commonly used measures of creative potential. Several extensive batteries are available but most research relies on one or two specific tests rather than a complete battery. This may limit generalizations because tests of DT are not equivalent. They are not always highly inter-correlated. Additionally, some DT tests appear to be better than others at eliciting originality. This is critical because originality is vital for creativity. The primary purpose of the present study was to determine which test of DT elicits the most originality. Seven measures of DTwere administered on a sample of 611 participants in eight Arabic countries. The tests were Figural, Titles, Realistic Presented Problems, Realistic Problem Generation, Instances, Uses, and Similarities. The Quick Test of Convergent Thinking, Runco’s Ideational Behavior Scale, and a demographic questionnaire were also administered. A linear mixed model analysis confirmed that the originality scores in the DT tests differed by test. Post-hoc tests indicated that the Titles and Realistic Problem Generation tests produced the highest mean originality scores, whereas the Realistic Presented Problems test produced the lowest mean originality scores. These differences confirm that research using only one DT test will not provide generalizable results.

653 LAPAROSCOPIC TOUPET FUNDOPLICATION RARELY INFLUENCES THE DECLINE IN FEV1 SEEN AFTER LUNG TRANSPLANT

2021 ◽  
Vol 34 (Supplement_1) ◽  
Author(s):  
Adam Frankel ◽  
Trina Keller ◽  
Syeda Farah Zahir ◽  
David Gotley
Keyword(s):  
Lung Transplant ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Least Squares Method ◽  
Organ Transplant ◽  
Case Series ◽  
Solid Organ Transplant ◽  
Solid Organ ◽  
Toupet Fundoplication ◽  
Laparoscopic Toupet Fundoplication

Abstract   Lung allografts have the shortest survival of any solid organ transplant. The leading cause of chronic lung allograft dysfunction (CLAD) is bronchiolitis obliterans syndrome (BOS). The aetiology of BOS remains poorly understood, with infections, immunosuppression and gastro-oesophageal reflux disease (GORD) amongst the proposed co-factors. A recent systematic review of GORD and BOS examined six retrospective case series with relatively small numbers and conflicting results. Our dataset is the largest cohort reported to date. Methods Retrospective review of a prospectively maintained database containing 149 consecutive lung transplant recipients undergoing laparoscopic Toupet fundoplication. A single expert surgeon (&gt;5000 procedures) with published high-quality long-term outcomes in the non-transplant population did the operations. All were referred with symptoms of GORD and/or positive 24-hour ambulatory pH study. FEV1 was measured at three time points before (6, 3 and 1 month) and after (3, 6 and 12 months) surgery. Data were analysed using random intercept generalised linear (mixed) models to examine changes in FEV1 across time, as well as graphical methods (least squares method for FEV1 trendlines and two-tailed t-test). Results Median age was 56 (IQR 44–66) years; 84/149 were male. 132 had bilateral sequential single lung transplantation. The underlying pathologies were representative—emphysema, cystic fibrosis, interstitial lung disease. 8 patients died within 6 months of fundoplication. Using a linear mixed model there was no significant change in FEV1 across time after surgery compared with the last pre-operative measurement (p = 0.48). A significant reduction in FEV1 was seen in those undergoing fundoplication after CLAD was diagnosed (1.47 L, 95% CI 1.21–1.72, p &lt; 0.001). There was no change in trajectory of FEV1 when trendlines for each patient were analysed (p = 0.777). Conclusion As with any solid organ transplant, lung allografts unfortunately suffer failure with time. Laparoscopic Toupet fundoplication performed in a high-volume centre by an experienced surgeon did not appear to alter this. In particular, once CLAD is diagnosed it seems that the decline in function (FEV1) is accelerated and cannot be salvaged by fundoplication. A minority of patients had their declining FEV1 stabilised or improved by surgery, but it is not yet possible to predict response.

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